The present invention relates in general to a blood lancet device for obtaining a drop of blood for testing. In particular, the present invention provides an adjustable tip for a blood lancet device which allows for several different depths of skin puncture.
It is now general practice in developed countries for diabetics to test their blood sugar levels several times a day. This necessitates the use of some kind of finger lancing device to obtain a drop of blood for testing. Presently, most lancet devices have one or, at most, two different depths of skin puncture and depth is changed by removing the tip and replacing it with another. This is inconvenient since the extra tip must be carried about and can be misplaced. An improved system would allow for finer gradations of strike depth and allow adjustments to be made quickly without having to change tips. Most persons have slightly different thickness of skin on different fingers. For example, the index finger is commonly more calloused than the middle or ring fingers. By varying the puncture depth to just the right degree, pain can be minimized and, at the same time, an adequate drop of blood can be drawn for testing.
A prior art adjustable tip device, the "Softclix," is presently manufactured by the Boehringer Mannhelm Company. The "Softclix" tip can be termed a "single bottom" device because that area of the tip which rests against the skin is but a single layer of plastic.
In the Boehringer device, the end of the tip is threaded and skin puncture depth is adjusted by merely rotating the tip clockwise or counterclockwise. This straightforward method of depth adjustment is possible because Boehringer uses a custom lancet which is notched to fit precisely in the lancet carrier. Therefore, the lancet travels exactly the same distance each time that the Boehringer device is fired.
The most commonly used lancet does not avail itself of this simple solution to varying the depth of skin puncture. The generic lancet has no notch that would allow it to be positioned in exactly the same way each time it is loaded into the lancet carrier. A different method must therefore be used to reliably vary the depth of strike.
The prior art also includes the adjustable tip lancet mechanism of the Bodicky et al U.S. Pat. No. 4,895,147 dated Jan. 23, 1990. That patent teaches a relatively complex "single bottom" tip that includes a mechanism for applying a vacuum to the puncture site. The prior art also includes the Slama U.S. Pat. No. 4,469,110 dated Sep. 4, 1984. The Slama device adjusts penetration depth by rotating the threaded sleeve 10 relative to the body 2. The Slama device is a "single bottom" device using relatively expensive threads to achieve adjustable depth penetration. The patent does not teach a "double bottom" and does not teach means for holding the parts in position to achieve a given depth repeatedly.
The technique herein described uses a "double bottom" tip in which the shoulder of the lancet provides the stop to the lancet's movement when it abuts against the "inner bottom." The position of the "outer bottom" can be varied by the user by turning it against a helical camming surface. Molding of the helical groove is facilitated by placing the upper and lower surfaces of the groove in separate plastic parts which are then pressed together.
The present design allows all these objectives to be obtained while keeping the cost to a minimum since only three parts are needed to make the tip. The design also allows the tip to be made sufficiently small in diameter so that it matches the barrel size of commonly used pen-like devices. The entire device taken together is therefore aesthetically pleasing.
A primary object of the invention is to provide an adjustable tip for a blood lancet device capable of use with the most commonly used lancet presently available.
A further object of the invention is to provide an adjustable tip for a blood lancet device which is simple in design and relatively inexpensive to manufacture by using only three parts.
Further objects and advantages of the invention will become apparent from the following description and drawings wherein: